**Core Concept**
A deviated nasal septum (DNS) is a common condition characterized by a displacement of the nasal septum, which is the cartilaginous and bony wall that separates the two sides of the nasal passages. Septal deviation can lead to various symptoms, including nasal obstruction, difficulty breathing, and recurrent sinusitis. Surgical correction of DNS is often considered for severe cases that do not respond to conservative management.

**Why the Correct Answer is Right**
Marked septal deviation (option B) is a common indication for surgical correction of DNS. In severe cases, the deviated septum can cause significant nasal obstruction, leading to symptoms such as difficulty breathing, sleep apnea, and recurrent sinusitis. Surgical correction involves repositioning or removing the deviated septum to improve nasal airflow and alleviate symptoms. This procedure is typically recommended for patients with marked septal deviation who have failed conservative management or have significant symptoms.

**Why Each Wrong Option is Incorrect**
**Option A:** A septal spur with epistaxis (nosebleed) may require surgical intervention, but it is not the primary indication for surgery in the context of DNS. Septal spurs can be managed conservatively with nasal decongestants and topical vasoconstrictors.

**Option C:** Persistent rhinorrhea (runny nose) is a common symptom of DNS, but it is not a standalone indication for surgery. Conservative management with nasal saline irrigations and decongestants is often effective in managing rhinorrhea.

**Option D:** Recurrent sinusitis may be associated with DNS, but surgery is not always the first line of treatment. Conservative management with antibiotics and nasal saline irrigations is often effective in managing sinusitis.

**Option E:** Prolonged DNS is not a specific indication for surgery. DNS is a chronic condition that may require ongoing management, but surgery is typically reserved for severe cases with significant symptoms.

**Clinical Pearl / High-Yield Fact**
A key clinical pearl is that patients with DNS are more likely to develop chronic rhinosinusitis, allergic rhinitis, and nasal polyps. Therefore, a thorough evaluation of the nasal passages and sinuses is essential in patients with DNS to identify and manage associated conditions.

**Correct Answer:** B. Marked septal deviation.